P0520 indicates that the engine control module (PCM) has detected a fault in the circuit of the engine oil pressure sensor or switch. This code does not necessarily mean the oil pressure itself is abnormal, but rather that the electrical signal from the sensor is out of expected range or missing.
The sensor itself is the most common failure point. Internal wear, contamination, or electrical short can cause incorrect readings or an open circuit.
Worn insulation, broken wires, or corrosion at the sensor connector can interrupt the signal or cause a short to ground or power.
Insufficient oil or a failing oil pump can cause actual low pressure, which the sensor reports correctly, but the PCM may interpret the low signal as a circuit fault.
Worn bearings, clogged oil passages, or a failing oil pump can cause low oil pressure, triggering the code indirectly.
A defective engine control module is an unlikely cause. It should only be considered after thoroughly testing the sensor, wiring, and oil pressure.
It depends. If the oil pressure warning light is on or you hear engine noise, stop immediately to avoid engine damage. If only the Check Engine Light is on and oil level/pressure are normal, you may drive cautiously to a repair facility, but diagnosis is recommended soon.
The sensor is far more common. A faulty oil pump is possible but less frequent. Always test the sensor and wiring first, and verify actual oil pressure with a mechanical gauge before replacing the pump.
Often yes, but only if the sensor is the root cause. If the wiring is damaged or oil pressure is truly low, replacing the sensor alone will not solve the problem. Proper diagnosis is essential.
Almost never. The PCM is rarely the cause of this code. Many drivers are incorrectly told to replace it, but that is usually a waste of money. Only consider PCM replacement after all other possibilities have been ruled out.